Electromagnetic interference (EMI) affects the performance of electrical circuits. Reduction of sensitivity to EMI, as well as the reduction of radiated levels of EMI, is an important consideration in the design of electrical circuits and devices. With increasing power levels and frequency, spurious radiation emissions also rises. Conversely, circuits operating with reduced power levels are particularly sensitive to undesirable radiation.
Designers often rely on gaskets and other shielding measures to reduce EMI transmissions. An area of particular interest concerns adequate shielding for high density connectors. Density refers to the number of electrical connections in a given area of a connector. A typical high density connector has 100 pins in the space having dimensions of approximately 38 mm by 10 mm, or an area of 3.8 cm2. An example of an application calling for such a connector is the High Performance Parallel Interface-6400 (HIPPI-6400) protocol. HIPPI-6400 relates to high frequency, digital data transmissions at 6400 Mbit/s of data per direction. Common mode currents on outer shields due to capacitive coupling and poor bonding of shielding components can result in the failure to meet applicable EMI compliance standards.
High density connectors are also prone to undesirable capacitive coupling between the connector housing and individual pins within the connector. As capacitive coupling rises, so to do levels of EMI radiation.
One proposed solution to ameliorate EMI radiation involves gasketing between the connector nose and connector housing while reducing capacitive coupling with increased spacing. Proper assembly technique requires that the connector pins and receivers are filly mated at a time when the gasket material, positioned between the nose of the connector backshell and the housing for the electronic circuitry, is sufficiently compressed. In this state, the proper electrical connection is established at the connector halves and the gasket has sufficiently low impedance with the housing such that an effective EMI seal is established. However, manufacturing tolerances often frustrate achievement of this result. In some cases, the connector pins will have reached the bottom of the connector receiver before the gasket material is sufficiently compressed, resulting in a higher impedance coupling to the housing and undesirable EMI leakage. If the connector jackscrews are tightened beyond a point where the connector assembly is fully mated, then it is likely that the connector, standoffs, or connector jackscrews will be damaged.
For the reasons stated above, and for other reasons stated below which will become apparent to those skilled in the art upon reading and understanding the present specification, there is a need in the art for a connector assembly to address the problem of undesirable EMI transmissions without adversely effecting the electrical connection.